Work based effort driven task load sharing to resources not yet available, help!

Hi,

My scenario:

I have 2 teams.  The teams consist of 2 people each, working back to back 2:1 roster (2 weeks on, 1 week off). 

Their working hours are 6AM to 6PM. 

The rosters are created from a new base calendar of those hours everyday and they have a T1 T2 working hours calendar based from that, with a dual exception to cover the week properly recurring every 3 weeks on alternating weeks respectively.

Looks sort of like this:

My tasks are work based effort driven tasks, all dependent on the previous task. 

The tasks are all assigned the 6AM-6PM everyday calendar, as the work is always available to any resource that is there, the resources are generic and shareable.

My estimation team give me a bucket of hours, which are entered to the work column of the task

What I want to achieve is to to simply assign all of my resources to all of my tasks and resources are always consumed on a first come first served basis when assigning them to work based tasks dependent on availability without sharing the tasks if resources are unavailable.  So it ends up looking like the team planner above. (which has been manually adjusted in the task usage screen as a result of the issue I am having)

I'm having an issue where I as soon as I assign all the resources, it shares them across all of them, independently of the team being available.

Which goes on to look like this:

Which is a complete and utter mess and gives no real representation of a real life use of hours.

I can get it to look a little better if I only assign the first 2 team members to the first couple of tasks but I would prefer it just to consume resources correctly.

I've quizzed a few experienced users and googled it to death and I can't find any solutions to my problem.  Everyone keeps telling me it is an inherent issue of how MS Project processes it's information but I don't believe there is no way of achieving this outcome.

TIA.